Some of the world's richest people - including Warren Buffett, Mark Zuckerberg and Jeff Bezos - lost billions apiece on Monday as stocks took an ugly nosedive.

The Dow Jones Industrial Average plunged 1,175 points, or 4.6%, marking the largest one-day drop the blue-chip index has ever seen and wiping out its gains for the year. The Dow, which tracks 30 U.S. companies, is now down 2% so far this year. The S&P 500 and Nasdaq also fell by about 4% each on Monday.

Warren Buffett was hit the hardest by the sell-off: The drop shaved $5.3 billion off his net worth --a nearly 6% drop in just one day. He is still the third-richest person in the world with a net worth of $84.6 billion, according to Forbes' real-time billionaire rankings.

Facebook CEO Mark Zuckerberg was next in line, shedding $3.6 billion, or 4.7% of his net worth, as shares of his social media company dropped 5%. He finished the day with $73.1 billion to his name.

Amazon's Jeff Bezos, the richest person on the planet, saw his fortune drop $3.2 billion. That erases the $3.2 billion he gained one day last week after his company announced blockbuster quarterly results. He is still worth an astounding $115.7 billion, which puts him $25 billion ahead of the second-richest person on the planet, Microsoft cofounder Bill Gates.

Altogether, the six billionaires who suffered the most from the market rout saw their fortunes shrivel by a whopping $18.8 billion in a single day. Many of the world's richest people have their net worth tied up in shares of their publicly traded companies and are vulnerable to fluctuations in the market.

To be sure, these billionaires have benefited hugely from a relentless bull market that is coming up on its nine-year anniversary. The S&P 500 gained 19% in 2017, driven in part by record corporate profits and an improving economy. Jeff Bezos, for instance, has become $28 billion richer in just the last four months as shares of Amazon rose 30%.